ECG-synchronized cardiac MR imaging: method and evaluation.

Lanzer, Peter; Barta, Christiane; Botvinick, E. H.; Wiesendanger, H. U. D.; Modin, Gunnard; Higgins, Charles B.

doi:10.1148/radiology.155.3.4001369

Cited by 111 publications

(45 citation statements)

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“…Magneto hydrodynamic (MHD) effects severely disturb the electrocardiogram (ECG) [61][62][63] commonly applied for cardiac triggering and gating at clinical field strengths [64][65][66] (Figure 4). Distortions of the ECG's S-T segment are caused by the increased MHD impact during systolic aortic flow [67].…”

Section: Ancillary Devices For Cardiac Synchronizationmentioning

confidence: 99%

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

Huelnhagen

Paul

et al. 2017

Front. Phys.

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Cardiovascular magnetic resonance imaging (CMR) has become an indispensable clinical tool for the assessment of morphology, function and structure of the heart muscle. By exploiting quantification of the effective transverse relaxation time (T 2 * ) CMR also affords myocardial tissue characterization and probing of cardiac physiology, both being in the focus of ongoing research. These developments are fueled by the move to ultrahigh magnetic field strengths, which permits enhanced sensitivity and spatial resolution that help to overcome limitations of current clinical MR systems with the goal to contribute to a better understanding of myocardial (patho)physiology in vivo. In this context, the aim of this report is to introduce myocardial T 2 * mapping at ultrahigh magnetic fields as a promising technique to non-invasively assess myocardial (patho)physiology. For this purpose the basic principles of T 2 * assessment, the biophysical mechanisms determining T 2 * and (pre)clinical applications of myocardial T 2 * mapping are presented.Technological challenges and solutions for T 2 * sensitized CMR at ultrahigh magnetic field strengths are discussed followed by a review of acquisition techniques and post-processing approaches. Preliminary results derived from myocardial T 2 * mapping in healthy subjects and cardiac patients at 7.0 T are presented. A concluding section discusses remaining questions and challenges and provides an outlook on future developments and potential clinical applications.

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Section: Ancillary Devices For Cardiac Synchronizationmentioning

confidence: 99%

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

Huelnhagen

Paul

et al. 2017

Front. Phys.

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“…To compensate for cardiac motion, measurements are ECG gated [46]. The signal from the ECG enables triggering on the R-wave and the selection of the time delay for image collection.…”

Section: Motion Compensationmentioning

confidence: 99%

Magnetic Resonance Imaging of the Heart : Image quality, measurement accuracy and patient experience

Ahlander¹

2016

Linköping University Medical Dissertations

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Background: Non-invasive diagnostic imaging of atherosclerotic coronary artery disease (CAD) is frequently carried out with cardiovascular magnetic resonance imaging (CMR) or myocardial perfusion single photon emission computed tomography (MPS). CMR is the gold standard for the evaluation of scar after myocardial infarction and MPS the clinical gold standard for ischemia. Magnetic Resonance Imaging (MRI) is at times difficult for patients and may induce anxiety while patient experience of MPS is largely unknown. Aims: To evaluate image quality in CMR with respect to the sequences employed, the influence of atrial fibrillation, myocardial perfusion and the impact of patient information. Further, to study patient experience in relation to MRI with the goal of improving the care of these patients. Method: Four study designs have been used. In paper I, experimental cross-over, paper (II) experimental controlled clinical trial, paper (III) psychometric crosssectional study and paper (IV) prospective intervention study. A total of 475 patients ≥ 18 years with primarily cardiac problems (I-IV) except for those referred for MRI of the spine (III) were included in the four studies. Result: In patients (n=20) with atrial fibrillation, a single shot steady state free precession (SS-SSFP) sequence showed significantly better image quality than the standard segmented inversion recovery fast gradient echo (IR-FGRE) sequence (I). In first-pass perfusion imaging the gradient echo-echo planar imaging sequence (GREEPI) (n=30) had lower signal-to-noise and contrast–to-noise ratios than the steady state free precession sequence (SSFP) (n=30) but displayed a higher correlation with the MPS results, evaluated both qualitatively and quantitatively (II). The MRIAnxiety Questionnaire (MRI-AQ) was validated on patients, referred for MRI of either the spine (n=193) or the heart (n=54). The final instrument had 15 items divided in two factors regarding Anxiety and Relaxation. The instrument was found to have satisfactory psychometric properties (III). Patients who prior CMR viewed an information video scored significantly (lower) better in the factor Relaxation, than those who received standard information. Patients who underwent MPS scored lower on both factors, Anxiety and Relaxation. The extra video information had no effect on CMR image quality (IV). Conclusion: Single shot imaging in atrial fibrillation produced images with less artefact than a segmented sequence. In first-pass perfusion imaging, the sequence GRE-EPI was superior to SSFP. A questionnaire depicting anxiety during MRI showed that video information prior to imaging helped patients relax but did not result in an improvement in image quality

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“…For respiratory motion, breath-holding may be used for short acquisi- tions and respiratory gating or phase-encode reordering, [30][31][32] for longer scans. Similarly for offsetting cardiac motion, cardiac gating, 33 a method of synchronizing data acquisition with the cardiac cycle, is available, whereas gradient-moment nulling has been proposed 34 for reducing pulsatility artifacts from flowing blood.…”

Section: Motion Compensationmentioning

confidence: 99%

Motion-Compensation Techniques in Neonatal and Fetal MR Imaging

Malamateniou

Malik

Counsell

et al. 2012

AJNR Am J Neuroradiol

111

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SUMMARY:Fetal and neonatal MR imaging is increasingly used as a complementary diagnostic tool to sonography. MR imaging is an ideal technique for imaging fetuses and neonates because of the absence of ionizing radiation, the superior contrast of soft tissues compared with sonography, the availability of different contrast options, and the increased FOV. Motion in the normally mobile fetus and the unsettled, sleeping, or sedated neonate during a long acquisition will decrease image quality in the form of motion artifacts, hamper image interpretation, and often necessitate a repeat MR imaging to establish a diagnosis. This article reviews current techniques of motion compensation in fetal and neonatal MR imaging, including the following: 1) motion-prevention strategies (such as adequate patient preparation, patient coaching, and sedation, when required), 2) motion-artifacts minimization methods (such as fast imaging protocols, data undersampling, and motion-resistant sequences), and 3) motion-detection/correction schemes (such as navigators and self-navigated sequences, external motion-tracking devices, and postprocessing approaches) and their application in fetal and neonatal brain MR imaging. Additionally some background on the repertoire of motion of the fetal and neonatal patient and the resulting artifacts will be presented, as well as insights into future developments and emerging techniques of motion compensation.ABBREVIATIONS: bFFE ϭ balanced fast-field echo; FLASH ϭ fast low-angle shot; G RO ϭ readout gradient; NSA ϭ number of signal averages; PROPELLER ϭ periodically rotated overlapping parallel lines with enhanced reconstruction; RF ϭ radio-frequency M R imaging is an ideal diagnostic technique for the evaluation of infants and fetuses 1-7 because of the absence of ionizing radiation, the superior contrast of soft tissues compared with sonography, and the availability of different contrast options (T1-weighted, T2-weighted, and diffusion-weighted imaging, Fig 1) to improve characterization of both anatomy and pathology. However MR imaging remains a relatively slow technique, with scanning times for most applications in the order of seconds to minutes, leaving them susceptible to motion artifacts. The normally mobile fetus and the unsettled neonate present a major difficulty because the presence of motion during a long acquisition will decrease image quality in the form of motion artifacts (Fig 2), hamper accurate image interpretation, and often necessitate a repeat MR imaging to establish a diagnosis. This may have major emotional implications for parents and can stress the tight budgets of health care providers.

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ECG-synchronized cardiac MR imaging: method and evaluation.

Cited by 111 publications

References 0 publications

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

Magnetic Resonance Imaging of the Heart : Image quality, measurement accuracy and patient experience

Motion-Compensation Techniques in Neonatal and Fetal MR Imaging

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